The present invention relates to a new and improved method of adjusting the contact pressure of a rolling mill for rolling a web of material, the rolling mill comprising at least one controlled deflection roll equipped with a plurality of hydrostatic pressure elements operated by means of a hydraulic pressure medium. The invention further relates to apparatus for the performance of the aforesaid method.
Controlled deflection rolls -- also sometimes referred to as rolls with bending compensation -- equipped with hydrostatic pressure elements are known to the art, for instance, from British Pat. No. 641,466 and U.S. Pat. Nos. 3,119,324 and 3,802,044. With these constructions of rolls, a rotatable roll shell is supported upon pressure elements in the form of pistons, which are guided at a stationary central support extending through the shell. The piston-like elements may be guided either in cylindrical bores provided in the support or a part connected therewith, or else each such piston-like pressure element may itself contain the cylindrical bore and be guided upon a respective associated pin-like projection provided at the support, typically for instance as shown in FIG. 4 of the aforementioned U.S. Pat. No. 3,802,044, the disclosure of which is incorporated herein by reference. These prior art controlled deflection rolls allow for the required deformation of the roll shell irrespective of the flexure or deflection of its support.